(1) Field of the Invention
This invention relates to a method of producing bio-active glass or glass-ceramics which are useful for artificial tooth roots or artificial bones
(2) Prior Art
Traditionally, glass is produced by a melting method or a VAD (Vapor-Phase Axial Deposition) method, but sol-gel methods have recently become common because they enable a glass to be synthesized at a low temperature and with a high degree of purity, and because they are free from any restrictions on the range of vitrification. A sol-gel method is a method in which a metal alkoxide is hydrolyzed and polymerized so as to form a gel which is thereafter calcinated to produce glass or glass-ceramics.
Sol-gel methods which use silicon, phosphorus, and alkaline earth metal as components are unknown.
If trialkyl phosphate, which is an alkoxide of phosphorus, is used as a phosphorus component in accordance with the ordinary techniques of sol-gel methods, the hydrolyzation is so slow that unchanged trialkyl phosphate remains in the gel. Since the boiling point of trialkyl phosphate is comparatively low, the composition of the gel changes as the phosphorus component evaporates when the gel is calcinated.
If phosphoric acid is used as a phosphorus component together with an alkaline earth metal, the phosphoric acid forms salts by reacting with Ca or the like, and the salts precipitate, so that the system tends not be uniform